Apparatus for bonding material electrically

ABSTRACT

573,518. Seaming non-metallic sheet materials. RADIO CORPORATION OF AMERICA. Oct. 15, 1943, No. 16972. Convention date, Feb. 27. [Class 42 (i) ] [Also in Group XI] Two or more contacting dielectric parts A, B are bonded together by a method which comprises interposing the parts between a pair of electrically conductive rollers 45, 55 of sufficient mass and heat conductive properties for withdrawing effectively heat from the surfaces in contact therewith, applying high frequency electrical energy to the rollers and causing them to rotate so to extract heat from the outer surfaces of the parts to be bonded while permitting the inner surfaces of the parts to become sufficiently heated by the dielectric losses therein to bond the parts together. The high-frequency electric current is supplied from an oscillation generator 7 through a concentric cable 69, 71 to the two electrode rollers 45, 55 between which the work A, B is fed above a table 3. The roller 45, which is driven from the motor 11 through belt, spur, worm and adjustable frictiondisc gearing, may be carried adjustably on a pivoted frame. The roller 55 is urged downwardly, with the frame 51, by a spring 61 adjustable at 67. The roller 55 may be formed hollow and supplied with cooling fluid under pressure. A foot switch 75 energises both the motor 11 and generator 7, the output of the latter being varied by adjustments 7a, 7b. Separate feed rollers for the work may be used and preheating of the work between plate electrodes may be provided for. The roller 55 may be replaced by an endless belt of conducting material. Non-thermoplastic fabrics may be joined by feeding sheets of thermoplastic material, or by feeding a liquid binder of the thermosetting type, therebetween. The bonding between the strips A and B &amp;c. may be continuous or discontinuous. Specification 565,592 is referred to.

Oct. 10, 1950 5 Sheets-Sheet 1 Original Filed Feb. 27, 1943 a L V. U a A 7 7 W m B n m w. o u M a 0W 4 w b y j 7H/I 41 a (Ittorneg 6 m w 5 n M m m a Q a 2 w H Y 5, s n D 2 a u M 4 H S n N. 5 7 fl A R E C N HOYLER APPARATUS FOR BONDING MA'I'ERIAL ELECTRICALLY Oct. 10, 195( v orlginal Flled Feb 2'7, 1943 K Iiiiiliflffil Oct. 10, 1950 C. 'N. HOY LER APPARATUS FOR BONDING MATERIAL YELECTRICALLY Original 51155 Feb. 27', 1945 5 Sheets-Shed 5 Gttorncg Oct. 10, 1950 c. N. HOYLER 2,525,356

APPARATUS FOR BONDING MATERIAL ELECTRICALLY Original Filed Feb; 27, 1943- s spews-sheet 4 3 mentor 'EYRIL N. HIJYLER l cm. 1%

C(ttorneg Oct. 10, 1950 c, HQYLER 2,525,356

APPARATUS FOR BONDING MATERIAL ELECTRICAL-LY Original Filed Feb. 27, 1943 5 Sheets-Sheet 5 lhmcntor CYRH. N. HDYLER Patented Oct. 10, 1950 APPARATUS FOR BONDING MATERIAL ELEOTRICALLY Cyril N. Hoyler, Princeton, N. J assignor to Radio Corporation of America, a corporation of Dela- Ware Original application February 27, 1943, Serial No. 477,478. Divided and this application June 12, 1944, Serial No. 539,855

11 Claims.

This invention relates to apparatus for bonding materials electrically, and more particularly to electronic apparatus for sealing together two or more parts or layers of material at least one of which is thermoplastic in nature and is rendered tacky when heated, the present application being a division of my copending application Serial No. 477,478, filed February 27, 1943. The invention disclosed herein is in the nature of an electronic sewing machine in that it may be utilized for uniting two or more layers of material with seam-like bonds to provide either continuous or broken seams, as may be desired, whereby the parts are joined together.

It has been known, heretofore, to bond together two or more layers of thermoplastic material by the use of heat. For example, in the manufacture of rubber or rubberized raincoats, it is fairly common practice to unite two or more contacting layers of material by passing a heated roller thereover, or by subjecting the layers to pressure between heated plates. To effect a suitable bond, it is necessary that the heat penetrate through the layers to the contacting surfaces of the materials so that these surfaces will become plastic. Obviously, if the heat is applied to the several layers through the external surfaces thereof in a degree or quantity sufficient to render the contacting surfaces thereof plastic, the relatively outer portions of these layers also become sufficiently hot to render them plastic, and even hotter. As a result, considerable difiiculty has been encountered in the prior art in avoiding sticking of the material to the rollers or plates by means of which the heat is applied to the work. In many instances in the prior art, where sticking of the material to the rollers or the like has not been encountered, it has been found that much of the heat is conducted away through the applicators to the atmosphere instead of com centrating it in the work, thereby greatly reducing the efliciency of operation. I

The primary object of my present invention is to provide an improved apparatus for heat sealing plastic and the like materials which will be "entirely free from the above mentioned and other similar objectionable features found in prior art apparatus.

More particularly, it is an object of my present invention to provide an improved apparatus for heat sealing two or more parts of which at least one is rendered plastic and tacky when hot whereby the heat applied to the work will be concentrated in or confined very largely to the regions of the parts contiguous to the contacting surfaces thereof.

Another object of my present invention is to provide an improved apparatus for uniting or bonding together two or more layers of materials at least one of which is rendered tacky under the influence of heat, the apparatus being such that the bond can be effected thereby either along a continuous seam, as in conventional sewing machines employing stitches, or along a broken seam, as may be desired.

Still another object of my present inventionis to provide an improved apparatus for bonding materials as aforesaid by means of which parts of any desired form or configuration can be readily bonded together.

A further object of my present invention is to provide an improved apparatus for bonding materials as above set forth which readily lends itself to various fields of use, such as in the manufacture of clothing, in the packaging industry, in the manufacture of inflatable articles, etc.

It is also an object of my present invention to provide an improved apparatus for bonding materials as above set forth which can be operated easily even by one who is not highly skilled in such work, which is economical commercially, and which is highly efllcient in'use.

In accordance with my present invention, I make use of a high frequency electric field for developing heat in the parts to be bonded together, at least one of which is preferably a dielectric material which becomes plastic when heated to a certain temperature. The material or parts to be bonded together are passed between one or more pairs of cooperating electrodes which terminate a high frequency oscillation generator, the generator serving to set up between the electrodes a high frequency electric field which heats the thermoplastic material to plasticity by reason of the dielectric losses therein. The electrodes may be in the form of heat conductive rollers of such mass that they can conduct away through the outer surfaces of the contacting layers to be bonded together the heat developed therein in a region remote from the contacting surfaces thereof. In this way, the

'heat developed in the contacting parts is concentrated in or largely confined to the regions thereof which are contiguous to their contacting surfaces, so that only the latter regions will become plastic, but the relatively outer portions of the parts being bonded will not become plastic. Suitable means may be provided whereby the rollers will apply pressure to the material while it is plastic or tacky for completing the bond, and either the same or other, additional rollers may be utilized to feed the parts past the operating station where the heat is induced therein.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description of several embodiments thereof, when read in connection with the accompanying drawings, in which:

Figure 1 is a front elevational view, partly in section, of one form of apparatus constructed accord ng to the present invention,

Figure 2 is a side elevation thereof as seen from the right of Fig. 1,

Figure 3 is a fragmentary, detailed view of a modified form of roller mounting,

Figure 4 is a sectional, detailed view of a modified form of roller forming a part of this apparatus,

Figures 5 to 10, inclusive, are diagrammatic views showing various forms of electrode arrangements and other modifications of the present invention,

Figure 11 is a fragmentary sectional view of a composite part ca able of being formed by the ap aratus i lustrated in Fig. 10,

Figure 12 is a view partly in elevat on and partly in section of another embodiment of the present invention,

F ure 13 is a plan view of the apparatus shown in Fig. 12,

Figure 14 is a p an view of an article that may be formed according to the present invention,

Figure 15 is an end e e ation of still another form of apparatus embodying the present invention,

Figures 16 and 17 are, res ectively, fragmenta v top plan and sectional views of a composite article formed by the apparatus of Fig. 15,

Figures 18 and 20 are front elevational views of still further modificatiosn of the present invention,

Figures 19 and 21 are fragmentary p an views of com osite articles form d, respectively, by the apparatus of Figs. 18 and 20,

Figure 22 is a diagrammatic view i lustrating the ap lication of my present invention to a somewhat different form of compos te article,

Figure 23 is a fragmentary sectional view of the composite a ticle which may be made by the apparatus of Fig. 22,

Figures 24, 25 and 26 are, respectively, a side elevation, a front elevation, and a top, plan view of still another form of apparatus based upon the present invention, and

Figure 27 is a fragmentary sectional view of an additional composite article formed according to the present invention.

Referring more particularly to the drawings, wherein similar reference characters designate corresponding parts throughout, there is shown inFigs. 1 and 2, a metallic stand having a work supporting table or top 3 which may be of insulating material or a grounded metal plate and which is provided with an opening 5. Supported on and electrically grounded to the stand is an oscillation generator 1 of any suitable type for supplying high frequency energy. Upon the casing of the oscillation generator I rests a supporting base 9 on which are mounted a motor 55' and a standard l2. The motor includes a driving pulley |3 which is coupled by a belt to adriven pulley I! On the standard i2.

Fixed to the same shaft which carries the driven pulley I1 is a friction disk i9 with which mates a friction wheel 2|. The wheel 2| is keyed to and slidable on a shaft 23 carried by a bracket 25 on the standard l2 and is adjustable longitudinally along the shaft 23 by means of an adjusting screw 21 which carries an internally threaded sleeve 29 connected to the friction wheel 2 by an arm 3|. By manipulating the screw 2? one way or the other, the driven friction wheel 2| may be adjusted radially along the friction driving disk l9 and to one side or the other of the center of the disk |9 whereby to vary the speed and direction of rotation of the shaft 23.

On the upper end of the shaft 23 is a worm which meshes with a pinion 35 on the same shaft as a second pinion 31 which meshes with a large gear 39 on a shaft 4|. The shaft 4| is rotatably carried by a bracket 43 fixed to the upper portion of the frame I immediately under the top 3. A relatively large, massive, metallic roller 45 having good heat and electrical conductivity is fixed to the shaft 4| and extends up through the opening 5 so that its upper, peripheral portion is above the top 3. The roller 45 constitutes one of the operating electrodes and is electrically connected to ground by connection with the frame through the shaft 4| and the bracket 43.

The gear 39 meshes with a gear 41 on a shaft 49 which is rotatably carried by an insulated frame 5| above the work table or top 3. The frame 5| is pivotally mounted on a pair of set screws or adjustable trunnions 53 for movement in a vertical plane away from and toward the roller electrode 45. Cooperating peripherally with the electrode 45 is a second roller electrode 55 fixed to the shaft 49, the roller 55 being smaller than the roller 45 but nevertheless also being of substantial mass and made of good heat and electrically conductive material, such as metal. Secured to the upper portion of the frame and extending up past the top 3 is an insulated plate 51 on which the trunnions 53 may be mounted and to which is fixed a bracket 59. A coil spring 6| connects the bracket 59 with a screw 63 which may be adjusted on a tubular support 65 by means of a cooperating nut 6?. The tube is secured to the frame 5|, whereby the spring 5| constantly tends to bring the frame 5| down toward the bracket 59 and the roller 55 into engagement with the roller 45. By adjusting the nut 61, the pressure between the rollers 45 and 55 can be regulated.

The oscillation generator 1 is coupled to the rollers 45 and 55 by a concentric line of which the inner conductor 69 is electrically connected to the shaft 49, as by a terminal element 10 secured to the shaft 49, and thereby to the roller 55, and the outer conductor 1! is connected to the frame I by a, bracket 13. Thus, the rollers 45 and 55 constitute the terminal elements or output electrodes of the oscillation generator 1 and form an electrical condenser when in a separated relation. The oscillation generator 1 and the motor may be coupled to a suitable source of power either through a single foot switch 15 or through separate, independent switches, as may be found most desirable.

The apparatus thus far described may be employed very successfully to bond together two or more layers of dielectric material A and B and at least one of which is a plastic material which becomes tacky when hot. For the sake of illustration, let it be assumed that both of the layers A and B are of the same or similar plastic materials of this type. To bond the layers A and B together, it is merely necessary to bring them into contact with each other and feed them in between the rollers 45 and 55. The composite material A, B may be inserted between the r01- ers 45 and 55 by raising the frame 5| slightly so as to separate the two rollers, after which the roller 55 is brought down into engagement with the work which now rests on the roller 45. At this point, the nut 61 may be adjusted to provide the desired pressure between the two electrode rollers 55 and 45. The fo t switch is then operated to energize the generator 1, whereupon an electric field is established between the peripheries of the two electrodes 45 and 55. This field produces dielectric losses in the layers A, B which serve to heat them. However, the rollers 45 and 55 both have sufiicient mass to conduct away through the outer surfaces of the layers A. B (that is, thr ugh the upper surface of the layer A and the lower sur ace of the laver B) the heat developed in the relatively outer regions of the two layers, that is, the heat in the regions thereof contiguous to the r s ective rollers. As a result. only t e regions of the lavers A and B- which are conti uous to t eir contacting surfaces will remain hot. This c nfinement or concentrat on of the heat in the last mentioned regions of the lay rs A. B causes the contacting surfaces and t e imm diately c nti uous re ions to become lastic and tacky. The pressure aoplied to the layers A. B by the roll rs 45 and 55 then causes the tacky re ions to adhere to each ot er. At the same time. the rollers 45 and 55, r tat n in res onse to the gears 39 and 41, respectivelv, will feed the compos te, joined arts A. B for ard and a cont nuous seam. will be formed alon the area at which the arts A and B are bonded or joined together under the roller 55.

A machine such as th t described above has been used v ry successfully to bond to ether various plast c materials, such as those known c mmerciallv as Koroseal (manufactured by The B. F. Goodr ch Companw. Krene (manufactur d bv the Carbide and Car on Ch micals Cor r tion). Plio lm (manufactur d by The Goodyear Tire and Rubber Com any), and other s milar pla tic. dielectric materials. as well as rubber faced fabrics. fabric re n orced rubber sheets. and the like. In t e particular machine r f rr d to. the rollers 4 and 55 are both m de of steel and are both solid. being, resoectivelv, 6 inches and 1 /9, inches in diameter. The roller 45 is approximat ly inch thick and the r ller 55, which is preferablv crowned slightly, is inch thick. The g ars 39 and 41 are so pro ortioned that the peri heral speeds of the rollers 45 and 55 are the same.

The power in ut to the electrodes 45 and 55, the frequency of the energy sup lied by the oscillation generator 1, andthe s eed with which the composite parts A, B are fed between and past the two rollers, as well as the pressure of the rollerson the work, depend upon the nature of the material and the type of bond desired. I have found that the frequency of the energy may vary over a wide range and may be as low as 10 megacycles per second and as high as 100 megacycles per second, or even-higher, while the power supplied to the workv may vary from as low as 5 watts to as much as 150 watts or more. The frequency of the oscillator and the power output thereof may be controlled by suitable control elements Ia. and lb on the oscillator casing 1. Similarly, the pressure applied to the work may be as low as 25 pounds per square inch or as high as 300 poundsper square inch, but the pressure should not be too great or it may cause the plastic or tacky regions to spread or ooze out between the rollers. By way of example, it may be stated that, in bonding together two sheets of Pliofilm having a thickness of 0.002 inch, the work was fed between the rollers at a speed of about 20 inches per minute and the power supplied to the work was 10 watts at 15 megacycles per second, the pressure between the rollers being approximately pounds per square inch. In other cases, the work was fed past the rollers at speeds up to inches per minute and with various power inputs, at diflerent frequencies, and also at various pressures. Articles such as belts, icebags, hot water bottles and other similar containers, aprons, curtains, raincoats, and inflatable articles such as'football bladders, life-boats, and the like are merely illustrations of the various products that can be bonded together or sewn successfully with the apparatus of my present invention.

In some cases it may be desirable to so mount the rollers 45 and 55 that they are adjustable, as a unit, with respect to the work-supporting member 3, whereby the extent to which the roller 45 protrudes through the opening 3 may be adjusted to suit different working conditions. In such cases, instead of mounting the shaft 4| on the bracket 43 which is fixed to the frame I, the shaft 4| may be mounted on a bracket 43a which is pivotally mounted on the frame I, as shown in Fig. 3. Here, the plate 51 is not secured to the frame I but may also be adiustably mounted thereon so that it can swing with the assembly about the pivot shaft 43b of the bracket 43a as a center. Any suitable locking means (not shown) may be employed to lock the assembly in the adjusted position.

In the apparatus thus far described, the rollers 45 and 55 are of solid stock throughout. Where additional cooling is desired over and above that afforded by the rollers themselves and the surrounding atmosphere, the rollers may be made of hollow construction and supplied with a cooling fluid. By way of example, i there is shown in Fig. 4 a hollow holler 55 mounted on a hollow shaft 49a through which a suitable cooling fluid may be supplied under pressure, the fluid entering through the hollow shaft 49a and emerging through one or more apertures or openings 55a in either one or both of the end plates of the roller.

Under certain circumstances, it may not be desirable to rely solely upon the electrode rollers 45 and 55 to feed the composite material A, B through the machine, or it may even be deemed advisable not to have the rollers 45 and 55 perform any feeding action at all. In such cases, a pair of auxiliary feed rollers 11, i9 be provided as shown in Fig. 5. If the feed rollers Ti and 69 are placed close to the electrode rollers 45, 55, the former may also be arranged to apply pressure to the heated strips or layers A, B, and in such case, the electrode rollers 45 and 55 even be stationary. I

Sometimes, it may be desirable to have the larger electrode roller 45 act as a feed roller but not the smaller electrode roller. To cooperate with the roller 45 in feeding the material forward, there may be provided a third roller 8| which is power driven and is preferably constantly urged toward the roller by a coil spring t3. Such an arrangement is illustratedin 6.

With some materials, it may be desirable to preheat the composite part before subjecting it to the electric field between the electrodes 65, 55. For this purpose, one or more pairs of auxiliary electrodes 85 may be provided in advance of the electrodes c5, 55, as shown in Fig. 7. The electrodes 85 may or may not be coupled to the same oscillation generator as the electrodes 25, 55, and, in any case, the field between the electrodes 85 may be of different intensity than that between the electrodes 45, 55. Where it is advisable to subject the parts A, B to the electric field between the electrodes 85 for a longer period of time than that between the electrodes 45, the electrodes 85 may be made of relatively elongated, plate-like members. The latter may provide a field of smaller intensity for preheating the work, and the electrodes 2-5, 55 will provide the final heating by a field of stronger intensity.

As in the case of Fig. 0, auxiliary feed rollers Ti, 79 ma be provided to advance the work.

In some cases, the preheating electrodes 85 may not be practical, yet it may be desirable to subject the work to a. relatively long heating cycle. For this purpose, a metallic, endless belt 8? may be substituted for the electrode roller 55, as shown in Fig. 8. The belt is trained around a pair of conductive rol ers spaced from each other a substantial are over the periphery of the roller 45 whereby as parts A, B are caused to engage the roller '55 over substantially the aforesaid arc. Either one or both of the rollers may be suitably coupled to the shaft 49. An additional pressure roller 92, which may or may not be power driven, is preferably provided between the strands of the belt 8's to apply the requisite pressure to the work.

Occasionally, the material to be bonded is such that arcing may take place therethrough between the two electrodes 35 and 55. Also, in some instances, it ma be found that the rollers 5-5 and 55 draw the heat out of the work too rapidly to permit the inner, contiguous regions thereof to remain tacky long enough to be brought into sufficiently intimate relation for bonding. To overcome these difficulties, the composite layers A, B may be fed past the electrodes between strips of dielectric material C, D as shown in Fig. 9. The materials C D may or may not be thermoplastic and they may even be of the same materials as the layers A, B. By using the strips C, D, the tendency for arcing is greatly reduced, as is also the tendenc for the heat to fiow out of the layers A, B. In addition, the tendency for the layers A, B to become deformed somewhat is greatly reduced, thereby providing a seal or sea-m of greater strength.

The invention has been described thus far with particular emphasis on bonding together two layers of which both are plastic. It is quite possible, however, to employ the present invention equally well for bonding plastic to nonplastic material, or, where a plastic binder is used, to unite two non-plastic materials. The present invention may also be utilized to great advantage in reinforcing one or more thermoplastic layers with one or more non-thermoplastic layers. Thus, in Figure 10, a strip or layer of fabric or other suitable non-thermoplastic material E is placed between the thermoplastic strips A, B and fed therewith between the electrodes 45 and 55. The regions of the layers or strips A and B which are contiguous to the reinforcing strip E become plastic and tacky as above described and the two softened, tacky portions flow into the interstices of the fabric to become united to each other and to the reinforc ing strip. The resulting composite part is shown in Fig. 11.

Instead of reinforcing thermoplastic parts as above described, the present invention may be practiced for uniting two or more non-thermoplastic layers with the aid of an intermediate thermoplastic layer, as shown, for example, in Figs. 22, 24, 25 and 26. In Fig. 22 are shown two fabric or similar non-thermoplastic layers F and G fed between the electrodes 45, 55 with an in terposed layer of thermoplastic bonding material H which penetrates into the fabric or like layers F, G when it has become plastic. The resulting, composite, laminated part is shown in Fig. 23. Where it is preferred to use the thermoplastic bonding material in the form of a liquid rather than as a solid sheet or layer H, an arrangement such as that illustrated in Figs. 24 to 26 may be employed. Here, the liquid binder K is supplied through a nozzle 93 which is connected to a supply tank 95, the nozzle 5'3 being disposed between the layers F and G in advance of the electrode rollers 45, 55, as besshown in Fig. 24. The binder K may be either thermoplastic or thermosetting material and is activated by the electric field between the electrodes 45, 55 to render it tacky. The pressure applied by the rollers 45, 55 completes the bond to provide a composite part similar to that shown in Fig. 23.

Fig. 14 shows, by way of illustration, one article that may be manufactured according to the present invention. The article illustrated is an apron 96 which is made of thermoplastic sheeting and includes a hem 96a and a fabric or other non-thermoplastic tie string 91. The hem 96a is formed by folding the edge of the sheet back on itself and passing the double layer formed thereby between the electrodes and 55 to bond the fold to the body of the apron. At the waist, the tie string 91 is inserted between the body and the fold and the composite assembly is bonded together in the manner shown in Fig. 10.

It will be apparent that, in manufacturing the apron, the material must be fed along a path other than a straight line in order to bond the angularly related edges, the curved corners, and the curved waist portion, although at the operating station 45, 55, the work may be fed instantaneously along a straight line. In some cases, it may be more desirable to form the entire hem and waist portion simultaneously. For this purpose, or where long seams of a particular configuration as desired, a pair of stationary electrodes 98 and 99 may be employed as shown in Figs. 12 and 13. These electrodes are shaped similarly to the work, or according to the shape of scam desired. The electrode 98 may be a thin, flexible, metallic sheet or foil which is supported on a resilient base I00 of sponge rubber or the like. The electrode 99 preferably is a bar of metal of relatively large mass. The material A with its marginal portion A folded back on itself to provide a hem, as shown in Fig. 13, is placed on the electrode 98 and the electrode 99 is placed over the'hem. The entire assembly may be placed in a suitable press and a dielectric block llll placed on electrode 99. High frequency current is supplied to the electrodes 98, 99 from the generator and pressure is simultaneously applied to the work by the press to complete the bond.

The various forms of the invention thus far described are designed to form continuous seams. In some cases, it may be found desirable to provide a broken or discontinuous seam which, in effect, results in spot welds, so to speak. For this purpose, either one or both of the roller electrodes 45, 55 may be constructed as shown in Fig. 15. In this form of the invention, the roller 45 is formed with a plurality of circumferentiallyspaced, radial projections I02 somewhat similar to the teeth of a spur gear. Theperipheral portion of each projection I02 cooperates with the periphery of the electrode 55 to form the spaced bonding joints or spot welds I03, as shown in 16 and 17, the materials A and B being unbonded between the joints I03, as represented by the somewhat exaggerated air spaces I04 in Fig. 17. To insure cutting off the effective electric held between the projections I02 and also to provide an adequate, continuous supporting surface for the work, the spaces between the projections I02 may be filled in with blocks I05 of insulating material.

.With the arrangement shown in Fig. 15, the joints or bonds I03 are spaced longitudinally along the work or composite part A, B. In some instances, it may be desirable to space the scams or bonded joints transversely across the work. For this purpose, either one or bothof the electrode rollers 45, 55 may be formed with circumferentially extending projections I02, I06 and I01, as shown in Fig. 18. The projections I02 are similar to those shown in Fig. 15, while the projections or ribs I06 and I0! are continuous and extend around the roller 45 in endless fashion, the three rows of projections I02, I06 and I0! being spaced from each other longitudinally along the roller 45. An arrangement of this sort simultaneously forms three rows of seams or bonds I03, I08 and I09, as shown in Fig. 19. The three rows of seams I03, I08 and I09 are arranged in parallel relation along straight lines extending longitudinally of the work, the seams or bonds I03 being spaced from each other longitudinally along the work and the seams or bonds I08 and I 09 being continuous and spaced from each other and from the seams I03 transversely of the work. Where the seams I08 and I09 are to be formed along a path which departs from a straight line, the projections I08 and I09 may be'suitably configured to the desired shape, as shown in Fig. 20,

and this results in seams or bonds H181; and I09a,

as shown in Fig. 21. v

Fig. 27 shows how a binding I II] of thermoplastic material may be applied to a thermoplastic sheet A. The binding III), with an inner filling of fabric or the like I I I, is formed with re-entrant folds II2 between which the edge of the sheet A is inserted, and the composite assembly is then passed between the electrodes 45 and 55 as above described, whereupon the binding N0, the filler III and the sheet A are bonded into one integral unit. Where the binding H0 is of transparent or translucent material, the filler III may be of colored material to provide a color contrasting effect. 7

Although I have shown and described my invention in considerable detail, it will, no doubt, be apparent to those skilled in the art that many other modifications and variations thereof are possible. .I therefore desire that my invention shall not be limited except insofar as is made iii 10 necessary by the prior art and by the spirit of the appended claims.

I claim as my invention: 1. In electricalapparatus for bonding together Y a plurality of contacting,dielectric parts with the aid of heat, the combination of a pair of rotary, electrically conductive rollers arranged for peripheral cooperation and constituting electrodes adapted to receive said parts therebetween, at least one of said rollers being provided with spaced peripheral projections adapted to cooperate with the periphery. of the other of said rollers, insulating means in the spaces between adjacent ones of said projections, means for setized in that said roller projections are spaced from each other circumierentially around said one roller.

3. Apparatus according toclaim 1 characterized in that said roller projections are spaced from each other longitudinally along said one roller.

4. Apparatus according to claim 1 character-' ized in that said roller projections extend cir-' cumferentially around said one roller in endless fashion and are spaced from each other longi-,

tudinally along said one roller.

a plurality of contacting, dielectric parts with the aid of heat, the combination of a pair of electrically conductive, endless members arranged for peripheral cooperation and constituting electrodes adapted to receive said parts therebetween, means including a generator for setting up between said electrodes a high frequency electrostatic field at a predetermined operating frequency for producing dielectric losses in said parts whereby to heat said parts, means for maintaining said members in pressing engagement with said parts, means for feeding said parts continuously past said members, and means in at least one of said endless members for periodically varying the electrostatic fieldv at a relatively low repetitive rate with respect to the operating frequency as said parts are advanced and while said generator remains energized at said operating frequency whereby to periodically vary the heating effect on successive portions of said parts.

6. In electrical apparatus for bonding together a plurality of contacting, dielectric parts withthe aid of heat, the combination of a pair of cooperating electrodes positioned to receive said parts therebetween, means including a generator for setting up between said electrodes a high frequency electrostatic field at a predetermined operating frequency for producing dielectric losses in said parts whereby to heat said parts, means for advancing said parts past said electrodes, and means in at least one of saidelectrodes for periodically varying the intensity of said field at a relatively low repetitive rate with respect to the operating frequency as said parts are advanced and while said generator remains energized at said operating frequency, whereby to heat periodically successive portions thereof.

wer

7. In electrical apparatus for heating a dielectric workpiece to produce a prescribed change therein, the combination of a pair of cooperating electrodes positioned to receive said workpiece therebetween, one of said electrodes being movable relative to the other of said electrodes and including a portion adapted to be brought periodically into cooperative relation with said other electrode, means for setting up between said first named electrode portion and said other electrode a high frequency electrostatic field effective to heat said workpiece sufficiently to produce said prescribed change therein when said portion is in cooperative relation with said other electrode, means for advancing said workpiece past said electrodes whereby said first named electrode portion and said other electrode are brought into cooperative relation at successive portions of said workpiece as said workpiece is advanced past said electrodes, and means in said movable electrode for diminishing the effectiveness of said field during the intervals between successive times that said portion is in cooperative relation with said other electrode whereby to produce said prescribed change in said workpiece substantially only at such'times as said portion is in cooperative relation with said other electrode.

8. In electrical apparatus for heating a dielectric workpiece to produce a prescribed change therein, the combination of a pair of cooperating electrodes positioned to receive said workpiece therebetween, one of said electrodes being mov able relative to the other of said electrode and including a solid roller having a plurality of spaced portions each adapted, in turn, to be brought periodically into cooperative relation with said other electrode, means for setting up successively between each of said first named electrode portions and said other electrode a high frequency electrostatic field effective to heat said -11- workpiece sufficiently to produce said prescribed change therein when any one of said portions is in cooperative relation with said other electrode, means for advancing said workpiece past said electrodes whereby each of said first named electrode portions and said other electrode will be brought into cooperative relation at successive portions of said workpiece as said workpiece is advanced past said electrodes, and means for diminishing the effectiveness of said field during the intervals between the time that any one of said portions is in cooperative relation with said other electrode and the time that the next sucseeding one of said portions is in cooperative relation with said other electrode whereby to produce said prescribed change in said workpiece substantially only at such times as said portions are in cooperative relation with said other electrode.

9. In electrical apparatus for bonding together a plurality of contacting, dielectric parts with the aid of heat, the combination of a pair of relatively movable, spaced electrodes positioned toreceive said parts therebetween, said electrodes being relatively movable into and out of bonding relationship with each other, a high frequency oscillation generator continuously connected tosaid electrodes for setting up therebetween a high frequency electrostatic field for producing dielectric losses in said parts sufficient to heat said parts to bonding condition when said electrodes are in said bonding relationship, means for feeding said parts between said electrodes, and mechanism connected with at least one of said elec- 12 trodes for periodically moving said one electrode into said bonding relationship with the other of said electrodes as said parts are fed therebetween to thereby periodically heat successive portions thereof to bonding condition.

10. In an apparatus of the class described, the combination with a 'pair of spaced juxtaposed electrodes adapted to receive dielectric materials therebetween, one of said electrodes being provided with a main body portion and a well defined work contacting portion, the said body portion being designed to remain out of contact with the said materials and the said work contacting portion being designed to contact said materials to establish, with the other of said electrodes a high frequency electrical field in said materials, a high frequency oscillation generator connected to said electrodes, and mechanism associated with said electrodes for periodically bringing said Work contacting portion into opposed relationship with the other of said electrodes to establish said field.

11. In electrical apparatus for bonding together a plurality of contacting, dielectric materials, the combination of a pair of relatively movable, juxtaposed, spaced electrodes adapted to receive said materials therebetween, one of said electrodes being provided with a body portion and Work contacting portion, said work contacting portion being adapted to establish bonding relationship with the other of said electrodes, a high frequency oscillation generator connected to said electrodes for setting up therebetween a high frequency electrostatic field of predetermined frequency for producing dielectric losses in said materials suflicient to heat said materials to bonding condition when said electrodes are in said bonding relationship, means for feeding said parts between said electrodes, and mechanism associated with said electrodes for periodically bringing said work contacting portion into said bonding relationship with the other of said electrodes at a relatively low repetitive rate with respect to said predetermined frequency as said materials are fed between said electrodes and while said generator continues to operate at said predetermined frequency to thereby periodically heat successive portions thereof to bonding condition.

CYRIL N. HOYLER.

REFERENCES CITED The following references are of record in the.

file of this patent:

UNITED STATES PATENTS Number Name Date 1,097,895 Thomson May 26, 1914 1,315,239 Pierce et al Sept. 9, 1919 1,465,241 Townsend Aug. 14, 1923 2,087,480 Pitman July 20-, 1937 2,103,390 Salfisberg Dec. 28, 1937 2,125,758 Waters Aug. 2, 1938 2,231,457 Stephen Feb. 11, 1941 2,234,223 Ball Mar. 11, 1941 2,276,994 Milinowsky Mar. 17, 1942 2,322,298 Johnston June 22, 1943 ,324,068 Crandell July 13, 1943 2,334,485 Ettl Nov. 16, 1943 2,343,975 Hosfield Mar. 14, 1944 2,354,714 Strickland, Jr Aug. 1, 1944 FORHGN PATENTS Number Country Date 187,761 Switzerland Feb. 16, 1937 

